The present invention relates to a multi-flow gas-dynamic pressure-wave machine.
The single-flow pressure-wave machines in predominant use today are a source of noise nuisance. It is desirable to reduce such noise in response to the continuously hardening demands of environmentalists, and also in the justified interest of the public. A pressure-wave machine is disclosed, for example, in U.S. Application Ser. No. 932,954 of Nicolaus Croes et al, filed Aug. 11, 1978, now Pat. No. 4,232,999 the disclosure of which is incorporated herein by reference.
Various solutions have already been proposed to reduce the noise levels of such devices. In one of these proposals, viz., Swiss Pat. No. 398,184, it is suggested to subdivide the height of the rotor cells (i.e., the cells in which the pressure exchange between the gaseous working media takes place) in the radial direction by annular-cylindrical intermediate tubes to form several circular flows. It is intended thereby to position the fundamental frequency of the sound vibrations above the upper threshold of hearing of the human ear. The intended effect is not, however, achieved in this way since it only causes several oscillations of the same frequency to be superimposed upon one another and the fundamental frequency is retained.
The construction described in that patent also has disadvantages with respect to production. Due to the annular cross-section of the intermediate tubes and the uniformly thick cell walls, heat and centrifugal tensions are created which cause deformations and overloading of the rotor structure.
It is, therefore, an object of the invention to avoid these disadvantages.
Another object of the invention is to reduce the noise level produced by pressure wave machines.